TTC3-mediated ubiquitination of APPL1 is suppression involved in the anti-asthmatic effects of the substance P receptor antagonist WIN62577.

We have previously reported the accentuating effects of substance P and its receptor, Neurokinin-1 receptor (NK1R), on asthma. Here, we sought to define the role and mechanism of WIN62577, an NK1R antagonist, in asthma. Ovalbumin (OVA)-induced mice were treated with WIN62577 or dexamethasone to analyze airway hyperresponsiveness and inflammation. WIN62577 alleviated airway inflammation and remodeling in mice. Transcriptomic alterations in the lungs of mice were analyzed by RNA-seq. WIN62577 impaired the epithelial-mesenchymal transition (EMT) of mouse bronchial epithelial cells (BECs) and fibroblast-to-myofibroblast transition (FMT) by inhibiting the transcription of E3 ubiquitin-protein ligase TTC3. TTC3 overexpression impaired the therapeutic effect of WIN62577 in OVA-induced mice. TTC3 promoted the degradation of adapter protein containing PH domain (APPL1) via ubiquitination, thereby inhibiting the nuclear export of liver kinase B1 (LKB1) and the activation of AMPKα. Overexpression of APPL1 and induction of LKB1 nuclear export inhibited EMT of BECs and FMT of fibroblasts and alleviated airway remodeling in OVA-induced mice. Collectively, these data suggest that WIN62577 inhibition of TTC3 transcription promotes the stability of APPL1 and nuclear export of LKB1 to activate AMPKα and alleviate airway remodeling by impeding EMT of BECs and FMT of fibroblasts.